We were in San Francisco earlier in the week and got a chance to see the Samsung Epic 4G, a dual-mode 3G/4G hybrid smartphone that runs Google’s Android operating system. The Epic 4G is definitely the most unique Galaxy S smartphone model, outpacing its competitors like the Captivate on AT&T, Vibrant on T-Mobile, and Fascinate on Verizon Wireless.

Unlike its close cousins, the Epic 4G has some unique features that make it stand out from the pack. First, it’s the only 4G smartphone on the market from the Galaxy S family, running on Sprint’s growing WiMax network. Additionally, speaking of networks, Sprint will also enable Hotspot functionality, at a premium, that will work on either 3G (CDMA/EV-DO) or 4G (WiMax) where available. However, unlike the EVO 4G, made by HTC for Sprint, the Epic 4G will be limited to 5 connected devices to share the Epic 4G’s mobile broadband connection over WiFi rather than the EVO’s more generous 8 devices, though that won’t be a problem for most users who would only need to connect a laptop or two to have quick, ubiquitous net access.

The Epic 4G will also have a sliding keyboard, something that the other Galaxy S models from rival carriers lack. In addition to the gorgeous multimedia-ready, crisp, superb and bright Super AMOLED touchscreen display, the Galaxy S keyboard offers a comfortable, offset keyboard layout that makes it natural and reminiscent to keyboards on a PC. With separate keys, the keyboard feels responsive and more comfortable than the Droid 2 from Motorola for Verizon, and has quick shortcut buttons for the Android OS right within reach. The eyboard is less cramped and feels more spacious than that on the Sprint Samsung Intercept, giving touch typists a natural way to enter text in addition to the Swype on-screen keyboard feature.

Other features that help differentiate the Epic 4G and make the device a winner for many consumers include the front-facing web-camera, like the iPhone 4 and the EVO 4G, and also an LED flash on the rear camera, which can capture stills in 5-megapixel resolution and record videos in up to 720p HD.

Like other high-end smartphones, the Epic 4G offers a very comfortable experience with its ARM-based Hummingbird processor with integrated graphics. The processor gives the Epic 4G the ability to switch between landscape and portrait, via the built-in accelerometer, without lag or delay, enable rich gaming, and handles multitasking and apps without any hesitation. In fact, the Epic 4G is the only Samsung Galaxy S variant that allows for the TouchWiz Samsung UI to be operated in landscape mode, partially due to the fact that the device supports the landscape-oriented sliding keyboard. In addition to the accelerometer, a proximity sensor, WiFi, GPS, gyroscope, Bluetooth, and light sensor are all standard fare on this high-end smartphone.

For those who resisted the 4.3-inch HTC EVO 4G, either due to the behemoth screen size or due to the lack of a physical keyboard, the Epic 4G is the answer to naysayers for Sprint. The 4-inch Super AMOLED screen not only feels more compact, but in actual usage, I didn’t feel like I missed the 0.3-inch of extra screen real estate. With the keyboard and all the extra punches that Sprint’s packing into this model, which can be expanded to up 32 GB of memory via a micro SDHC card, you really can’t go wrong. For anyone considering the less expensive Android Samsung Intercept, I’d recommend taking the plunge for the Epic 4G at the end of the month–you’ll be a lot happier with the faster processor, faster network support, and Froyo will make your web experience a whole lot better, especially if you browse a lot of Flash-based webpages.